EVALUATION OF EXISTING MODELS FOR BOND CAPACITY OF NSM FRP

It is now nearly two decades since Fiber Reinforced Polymer (FRP) was first used as structural engineering materialandever since its main utilization has been in the strengthening of existing reinforced concrete structures. Flexural and shear strengthening of reinforced concrete elements using FRP are performed in two general methods: externally bonding FRP reinforcement (EBR) to element’s surface or putting FRP in the form of rod, laminate and strip in a pre-cut groove and filling it up with epoxy paste. The latter called near-surface mounted FRP (NSM) is more effective method as compared to EBR because higher values of FRP strain can be attained. In order to make an effective use of NSM FRP in strengthening of reinforced concrete structures, it is required to have an adequate understanding of the force transferring mechanism between junction of FRP and concrete.In this paper, three models are implemented and compared with 60 test results using different local bond-slip curves. The first two models are based on fracture mechanics but the second model uses finite element method. The third model is a rather complex closed-form modelbased on constitutive law and equilibrium. The result of the comparison asserts that the models have accurate predictions for the bond strength of NSM FRP.